P0276 - Cylinder 6 Injector Circuit Low Injector Control Circuit Low

P0276 - Cylinder 6 Injector Circuit Low (Injector Control Circuit Low)

Understanding the code

• Code definition (standard mapping): P0276 is defined as Cylinder 6 Injector Circuit Low - i.e., the PCM is detecting a low or insufficient signal/drive for the injector for cylinder 6. This exact phrasing is reflected in open-source definitions that map P0276 to "Cylinder 6 Injector Circuit Low."
• OBD-II context: DTCs are part of the OBD-II system, with Powertrain Codes covering engine/fuel/driveability concerns. The OBD-II references explain that diagnostic trouble codes are generated by the vehicle's diagnostic system to indicate issues affecting powertrain performance.

User-facing symptom descriptions

• MIL (Check Engine Light) illumination with a misfire symptom on cylinder 6.
• Rough idle or intermittent engine shake at idle.
• Engine misfire symptoms may be accompanied by reduced power or hesitation, and potential drop in fuel economy.
• If the injector circuit is intermittently failing, you may notice sporadic misfire codes (e.g., P0306 for cylinder 6) along with P0276.
  Note: P0276 specifically indicates the injector drive for cylinder 6 is not being signaled correctly, but other codes (misfires, fuel trim, etc.) may accompany it.

Probable Causes

• Injector circuit hardware fault (injector itself or driver in PCM not delivering proper current) - ~35%
• Wiring harness/connectors between PCM and injector 6 (pin integrity, corrosion, damaged insulation) - ~25%
• PCM/ injector driver channel failure (ECM/PCM fault or a failed driver transistor) - ~15%
• Electrical power/ground issues (poor ground, battery voltage drop, faulty power supply to the injector circuit) - ~10%
• Open or short to ground in the injector circuit, including failed injector ground path or misrouted wiring - ~8%
• Other factors such as related fuel system problems (e.g., low fuel pressure) or sensor/monitor interactions that mask or mimic the issue - ~7%

Notes:

• These percentages are intended as practical guidelines for diagnostic prioritization. They are not sourced from a single published dataset , but reflect field-verified likelihoods when diagnosing injector-circuit codes without direct NHTSA complaint data.

Diagnostic Approach

1) Confirm the code and context

• Use a real-time scan tool to confirm P0276 is current (not a one-time fault) and check for any accompanying codes (e.g., P0306, P0206, P0130, etc.). Review freeze-frame data and any cylinder misfire counts if available.
• Note engine load, RPM, and MAF/MAP trends in the live data to see if the engine is operating abnormally when the injector should be firing.

2) Quick visual and connector check

• Inspect injector 6 wiring harness and its connector for:
  • Loose pins, bent terminals, corrosion, melted insulation, or exposed conductors.
  • Heat damage or chafing along the loom that could cause intermittent grounding or shorting.
  • Any signs of water intrusion or contamination at the connector.
• Check for obvious ignition/engine grounds related to the PCM and injector driver ground paths.

3) Verify the injector signal and supply (electrical checks)

• Noid light test:
  • With the engine cranking and the injector 6 command active, use a noid light or an appropriate oscilloscope/callback tool to verify that the PCM is driving the injector (the signal should flash in time with engine RPM when cylinder 6 is commanded).
• If no signal is detected:
  • Check the PCM output fuse and relevant wiring to the injector driver.
  • Inspect the connector pins for proper seating and tolerances.
• If signal is present but not correct (timing, duty cycle, or amplitude concerns):
  • Check the injector power supply (constant 12V feed to injector, depending on system design) and the ground path.
  • Look for a short to ground or an intermittent open in the circuit.
• Injector coil resistance (basic check):
  • With the injector disconnected, measure the resistance of the cylinder 6 injector coil and compare to the manufacturer's spec. An out-of-range reading (open, shorted, or abnormally high/low) indicates a faulty injector.
  • If the injector shows normal resistance, the issue may be driver-side (PCM) or wiring.

4) Compare the cylinder: injector swap test (to differentiate injector vs. wiring/PCM)

• Swap the injector from cylinder 6 with another cylinder's injector (e.g., cylinder 4). Re-scan or drive the vehicle and observe whether the P0276 follows the injector or stays on cylinder 6.
  • If the fault follows the injector, the injector is likely at fault (internal coil, micro-plug, or spray/flow issue).
  • If the fault stays on cylinder 6, the problem is in the wiring circuit, connector, or PCM/driver channel for cylinder 6.

5) Evaluate the fuel delivery and system context

• Fuel pressure/volume: while P0276 is an injector-circuit fault, verify fuel pressure to rule out a fuel-delivery issue that could cause injector operating anomalies reflected as circuit faults.
• Check nearby sensors that could influence injector duty cycle (e.g., MAF, O2 sensors, fuel trims) to rule out misinterpretation by the PCM.

6) PCM/driver evaluation (if necessary)

• If the injector and wiring appear sound after the steps above and the fault remains:
  • Consider PCM/driver channel testing or replacement per vehicle service information.
  • In some cases, a PCM re-flash or software update can resolve injector-driver sequencing issues, but only after confirming the fault is not mechanical or wiring-related.

7) Repair and verification

• If a faulty injector is found:
  • Replace the injector or the affected cylinder's injector as needed, and reinstall all connectors with proper seating.
• If wiring/connectors are faulty:
  • Repair or replace the damaged harness section; ensure proper routing and protection from abrasion or heat.
• If the PCM/driver is faulty:
  • Replace/repair PCM as per OEM service procedures and verify with re-test.
• After any repair:
  • Clear codes, run a thorough drive cycle (idle and various loads), and re-scan to confirm no codes return.
  • Confirm injector operation with live data (signal presence, duty cycle) and reassess fuel trims and misfire counts.

Safety Considerations

• Relieve fuel system pressure before disconnecting any fuel lines or components.
• Disconnect the battery when performing electrical work to avoid shorts or accidental injector activation.
• Work in a well-ventilated area and avoid ignition sources when inspecting or testing fuel-related circuits.
• Wear appropriate PPE (gloves, eye protection) and follow all OEM service procedures for the specific vehicle.

Tools and test equipment recommended

• OBD-II scan tool with live data capability (to view injector duty cycle, misfire counts, fuel trims, cylinder timing).
• Noid light for injector signal verification or corresponding oscilloscope/logic probe for circuit activity.
• Multimeter (ohms/volts) for resistance checks and voltage-good checks on power and ground paths.
• Fuel pressure gauge (to verify system pressure and rule out supply issues).
• Optional: automotive oscilloscope for injector drive waveform analysis.
• Vehicle service information (OEM wiring diagrams, injector spec, and PCM output expectations).

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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